Sending http request repeatedly, more fast (async mode) - c++

Question

I need to send one request to server more quickly and repeatedly.
So I implemented code like this.
BOOL CTestDlg::OnInitDialog()
{
...
m_hInstance = InternetOpen(L"asynchttp", INTERNET_OPEN_TYPE_PRECONFIG,NULL,NULL,INTERNET_FLAG_ASYNC);
if(m_hInstance == NULL)
{
ErrorLog(L"InternetOpen Failed");
return TRUE;
}
if (InternetSetStatusCallback(m_hInstance,(INTERNET_STATUS_CALLBACK)&Callback) == INTERNET_INVALID_STATUS_CALLBACK)
{
ErrorLog(L"Set Callback Function Failed");
return TRUE;
}
m_hConnect = InternetConnect(m_hInstance, L"192.168.2.116", 8080,NULL,NULL,INTERNET_SERVICE_HTTP,INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE | INTERNET_FLAG_KEEP_CONNECTION,1);
if(m_hConnect == NULL)
{
if(DWORD dwError = GetLastError() != ERROR_IO_PENDING)
{
ErrorLog(L"Fail to Connect Server");
return TRUE;
}
WaitForSingleObject(hConnectedEvent, INFINITE);
}
CreateThread(0 , 0 , (LPTHREAD_START_ROUTINE)SendThread , 0 , 0 , 0);
return TRUE;
}
void __stdcall Callback(HINTERNET hInternet,DWORD dwContext,DWORD dwInternetStatus,LPVOID lpStatusInfo,DWORD dwStatusInfoLen)
{
switch(dwContext)
{
case 1:
{
SetEvent(hConnectedEvent);
}
break;
}
}
DWORD SendThread(LPVOID lpParam)
{
TCHAR *szAceptType[] = {_T("*/*") , NULL};
CString szContentType = _T("Content-Type: application/x-www-form-urlencoded\r\n");
char szPostData[MAX_PATH];
sprintf(szPostData , "num=1234&str=3240");
HINTERNET hRequest = HttpOpenRequest(m_hConnect, L"POST", L"/TestWeb/index.jsp", HTTP_VERSION , NULL , (LPCTSTR*)szAceptType , 0, 2);
while(1)
{
try
{
if (!HttpSendRequest(hRequest, szContentType, (DWORD)szContentType.GetLength(), szPostData,(DWORD)strlen(szPostData)))
{
if (DWORD dwError = GetLastError() != ERROR_IO_PENDING)
ErrorLog(L"SendRequest: Error = %d" , dwError);
}
}
catch (CException* e)
{
UNREFERENCED_PARAMETER(e);
}
Sleep(100);
}
return 0;
}
When execute or debug program, I saw this "SendRequest; Error = 1" log frequently.
And Server does not record anymore to database , after one or two request data recorded
It seems like HttpSendRequest API doesn't work correctly after error occured.
I aim to send one request to server more fast and more correctly, without loss.
Please teach me what is wrong problem.
Or if you got another best way, then please tell me.
Thanks.

Answer 1

Error code 1 is "Invalid Parameter".
You appear to be mixing ASCII (char and sprintf) and Unicode strings in your sample above. Have you tried with all Unicode strings (making szPostData a WCHAR array)? From MSDN: "There two versions of HttpSendRequest —HttpSendRequestA (used with ANSI builds) and HttpSendRequestW (used with Unicode builds)". It goes on to talk about when ERROR_INVALID_PARAMETER is returned. http://msdn.microsoft.com/en-us/library/windows/desktop/aa384247(v=vs.85).aspx
Also, I haven't used MFC in a long time, but I remember that you should call e->Delete() in your exception handler (unless you re-throw). The CException::Delete method will delete any thrown exception created on the heap (and do nothing otherwise).